WASHINGTON — In the middle of his crowded dinner in Buenos Aires with President Xi Jinping of China, President Trump leaned across the table, pointed to Robert Lighthizer, the United States trade representative whose skepticism of China runs deep, and declared, “That’s my negotiator!”

He then turned to Peter Navarro, his even more hawkish trade adviser, adding, “And that’s my tough guy!” according to aides with knowledge of the exchange.

Now, with talks between China and the United States set to begin this week in Beijing, Mr. Lighthizer, aided by Mr. Navarro, faces the assignment of a lifetime: redefining the trade relationship between the world’s two largest economies by Mr. Trump’s March 2 deadline to reach an agreement.

And he must do it in a way that tilts the balance of power toward the United States. His approach will have significant ramifications for American companies, workers and consumers whose fortunes, whether Mr. Trump likes it or not, are increasingly tied to China.

First, however, Mr. Lighthizer will need to keep a mercurial president from wavering in the face of queasy financial markets, which have suffered their steepest annual decline since 2008. Despite his declaration that trade wars are “easy to win” and his recent boast that he is a “Tariff Man,” Mr. Trump is increasingly eager to reach a deal that will help calm the markets, which he views as a political electrocardiogram of his presidency.

Mr. Trump has repeatedly told his advisers that Mr. Xi is someone with whom he can cut a big deal, according to people who have spoken with the president. On Saturday, Mr. Trump called Mr. Xi to discuss the status of talks, tweeting afterward that good progress was being made. “Deal is moving along very well,” Mr. Trump said.

The administration has tried to force China to change its ways with stiff tariffs on $250 billion worth of Chinese products, restrictions on Chinese investment in the United States and threats of additional levies on another $267 billion worth of goods. China has responded with its own tit-for-tat tariffs on American goods. But over a steak dinner during the Group of 20 summit meeting in Argentina, Mr. Xi and Mr. Trump agreed to a 90-day truce and to work toward an agreement that Mr. Trump said could lead to “one of the largest deals ever made.”

“It’s not some subtle shift; Trump has flipped since September,” said Derek Scissors, who studies China’s economy for the American Enterprise Institute. “He went from saying how he was going to slap tariffs on everything to all this talk about making the greatest deal ever.”

Mr. Lighthizer — whose top deputy will meet with Chinese officials this week ahead of more high-level talks in February — has played down any differences with Mr. Trump and views his role as ultimately executing the directive of his boss. But the trade representative, who declined to be interviewed, has told friends and associates that he is intent on preventing the president from being talked into accepting “empty promises” like temporary increases in soybean or beef purchases.

Mr. Lighthizer, 71, is pushing for substantive changes, such as forcing China to end its practice of requiring American companies to hand over valuable technology as a condition of doing business there. But after 40 years of dealing with China and watching it dangle promises that do not materialize, Mr. Lighthizer remains deeply skeptical of Beijing and has warned Mr. Trump that the United States may need to exert more pressure through additional tariffs in order to win true concessions.

When Mr. Lighthizer senses that anyone — even Mr. Trump — might be going a little soft on China, he opens a paper-clipped manila folder he totes around and brandishes a single-page, easy-reading chart that lists decades of failed trade negotiations with Beijing, according to administration officials.

“Bob’s attitude toward China is very simple. He wants them to surrender,” said William A. Reinsch, a former federal trade official who met him three decades ago when Mr. Lighthizer was a young aide for former Senator Bob Dole of Kansas. “His negotiating strategy is simple too. He basically gives them a list of things he wants them to do and says, ‘Fix it now.’”

Mr. Trump’s selection of Mr. Lighthizer last month to lead the talks initially spooked markets, which viewed the China skeptic’s appointment as an ominous sign. It also annoyed Chinese officials, who had been talking with the Treasury secretary, Steven Mnuchin, a more moderate voice on trade and the primary point of contact for Liu He, China’s top trade negotiator. Mr. Mnuchin has urged the president to avoid a protracted trade war, even if that entails reaching an interim agreement that leaves some issues unresolved.

Mr. Mnuchin, who attended the G-20 dinner, helped Mr. Trump craft an upbeat assessment declaring the Buenos Aires meeting “highly successful” in the presidential limousine back to the airport, according to a senior administration official.

The disparate views among Mr. Trump’s top trade advisers have prompted sparring — both publicly and behind the scenes.

In late 2017, when Mr. Lighthizer grew concerned that Mr. Mnuchin and Wilbur Ross, the commerce secretary, were wading too far into China matters, he enlisted Rob Porter, the president’s staff secretary at the time, to persuade Mr. Trump to draft a document designating Mr. Lighthizer the main trade emissary to China, according to a person who has seen the letter. Mr. Lighthizer has never used the document to defend his position, the person said, but he considers it an insurance policy of sorts.

During an Oval Office meeting with the trade team the fall of 2017, Mr. Lighthizer accused Mr. Mnuchin and Gary D. Cohn, the former National Economic Council director, of bad-mouthing him to free-trade Republican senators.

The argument grew so heated that the White House chief of staff, John F. Kelly, quickly pulled the combatants into the nearby Roosevelt Room and away from the president, where the argument raged on for a few more minutes, according to two witnesses.

Emily Davis, a spokeswoman for the United States trade representative, disputed the account.

Mr. Lighthizer has since worked to increase his own face time with Mr. Trump. He has joked to colleagues that he has more influence with Mr. Trump during winter months because he is able to hitch a ride on Air Force One during the president’s flights down to Mar-a-Lago, which is several miles from Mr. Lighthizer’s own $2.3 million waterfront condo in Palm Beach, Fla.

He used that access to argue to Mr. Trump that the United States has never had more leverage to extract structural reforms on intellectual property, forced transfer of technology from American companies and cybercrime. But while Mr. Trump has jumped at the chance to claim victory in changing China’s ways, experts say that what Mr. Lighthizer is demanding would require significant shifts in how Beijing’s central government and its manufacturing sector coordinate their activities, and that might simply not be possible in the short term.

“Good luck with that,” Mr. Scissors said.

Those who know Mr. Lighthizer say he will try to force concessions through a combination of pressure tactics, like tariffs, and public condemnation. Mr. Lighthizer — who described his own negotiating style as “knowing where the leverage is” during a 1984 interview — typically presents few specific demands during initial talks while publicly bashing efforts by the other side.

He used that approach during recent talks with Canada and Mexico to revise the North American Free Trade Agreement, criticizing foreign counterparts as intransigent and characterizing complaints by American businesses as pure greed.

Mr. Lighthizer’s unsparing view of China comes, in part, from his childhood in Ashtabula, Ohio, an industrial and shipping town on the Great Lakes hit by the offshoring of steel and chemical production. For much of his career, Mr. Lighthizer was a lonely protectionist voice in a Republican Party dominated by free traders, alternating between jobs in government and a lucrative private law career representing large American corporations like United States Steel in trade cases against China.

Mr. Lighthizer found his way into Mr. Trump’s orbit through his work in the steel industry, where he gained prominence by filing lawsuits accusing Japan and China of dumping metals into the United States, in violation of trade laws. In 2011, Mr. Lighthizer caught Mr. Trump’s eye with an opinion piece in The Washington Times, in which he defended Mr. Trump’s approach to China as consistent with conservative ideology and compared the future president to Republican icons like Ronald Reagan.

Taciturn in public and self-deprecating in private, Mr. Lighthizer sees himself as a serious player on the world stage: Two recent guests to Mr. Lighthizer’s Georgetown townhouse were greeted by the stern visage of their host staring down at them from an oil portrait on the wall.

The trade adviser is guarded around Mr. Trump, often waiting until the end of meetings to make his points and quietly nudging the president away from actions he views as counterproductive, current and former officials said. That was the case in mid-2017 when he cautioned the president against withdrawing unilaterally from the World Trade Organization, adding for emphasis, “And I hate the W.T.O. as much as anybody.”

He does not always get his way. In the wake of a new trade agreement with Mexico and Canada this fall, Mr. Lighthizer urged Mr. Trump to consider easing steel and aluminum tariffs on those countries and replacing them with less burdensome quotas. Mr. Trump rejected his plan, according to negotiators from all three countries.

A poker-faced Mr. Lighthizer broke the news to his Mexican and Canadian counterparts by declaring the proposal was inoperative, one of the officials said.

The president also ignored Mr. Lighthizer’s advice in early December when he announced that he intended to begin the six-month process of withdrawing the United States from Nafta in order to pressure House Democrats into passing the new United States-Mexico-Canada Agreement.

That threat undermined months of quiet negotiations between Mr. Lighthizer, labor groups and Democrats like Senator Sherrod Brown of Ohio and Representative Nancy Pelosi of California to try to win their support for the new trade deal. Mr. Trump has yet to follow through on his threat, and Mr. Lighthizer continues trying to work with Democrats to get the new trade deal approved.

“Bob is trying to provide stability and focus in a completely chaotic environment,” Mr. Brown said. “I can’t speak for Bob, but I am certain he is frustrated. How could you not be frustrated as the U.S. trade representative for a president who knows what his gut thinks but hasn’t put much of his brains into trade?”

maybe intending it as a compliment—craftily packaged together a number of small concessions and previously agreed upon initiatives which allowed Trump and his allies to hail the agreement as an American win. “This is a real vindication of the President’s trade policy,” Wilbur Ross, the Secretary of Commerce, told reporters as he travelled to the Midwest with Trump on Thursday.

In reality, the Europeans gave up little except their prior refusal to negotiate under threat.

.. Juncker’s pledge that the E.U. would import more U.S.-grown soybeans, for instance, formalized something that was likely to happen anyway. After Trump imposed hefty tariffs on Chinese steel and aluminum products, earlier this year, China responded by imposing equally hefty levies on U.S. agricultural exports, including soybeans. That made American soybeans prohibitively expensive for Chinese buyers

.. Brazil, traditionally the E.U.’s largest supplier, is now shipping more of its produce to China, encouraging the Europeans to shop elsewhere. “While China concentrates its purchases on Brazil, the rest of the world turns to the U.S.,

.. Looking years ahead, Norway’s reserves have plateaued, and the Europeans will eventually need alternative suppliers. U.S. producers could well be among them. But, again, such a result may well have occurred without Wednesday’s agreement.

.. Both sides provide subsidies or tax breaks to politically powerful groups, such as farmers, and to industries they deem strategically important, such as commercial-aircraft manufacturers in the E.U. and military contractors in the U.S. These policies proved sticking points when the Obama Administration and the E.U. engaged in unsuccessful negotiations about a transatlantic free-trade treaty, and they will almost certainly prove to be sticking points again.

.. One way to think of the outcome of Wednesday’s meeting is that Trump is happy to declare a victory whenever he can get away with it. However, a more optimistic reading of this week’s developments is that Trump has finally realized that he needs the E.U.’s support in his campaign against China’s much more overtly mercantilist trade practices, and that, in this area at least, the United States and Europe have common interests.

.. E.U. officials wanted to persuade the Trump Administration to pursue grievances against China through the World Trade Organization (W.T.O.), the global ruling body for trade disputes, rather than by dishing out tariffs unilaterally. The article also noted that Robert Lighthizer, the U.S. Trade Representative, a key player in the Trump orbit, is not necessarily averse to this idea.

.. “Comfortingly, there is mounting evidence that Mr Lighthizer is not out to torpedo the WTO,”

.. If Lighthizer could persuade Trump to go down this route, and his negotiating team could construct a common front with the E.U., there is a possibility that, sometime in the future, China might be persuaded to make some real concessions in areas like opening its markets and respecting intellectual-property rights. If that did occur, the Trump Administration could claim a genuine victory.

that they raise it to 4 percent of G.D.P., much higher than the bloated military spending in his own budget. He then claimed, falsely, to have won major concessions, and graciously declared that it is “presently unnecessary” to consider quitting the alliance.

Was there anything our allies could have done that would have mollified him? The answer, surely, is no. For Trump, disrupting NATO doesn’t seem to be a means to an end; it’s an end in itself.

.. While Trump rants about other countries’ unfair trade practices — a complaint that has some validity for China, although virtually none for Canada or the European Union — he hasn’t made any coherent demands. That is, he has given no indication what any of the countries hit by his tariffs could do to satisfy him, leaving them with no option except retaliation.

.. So he isn’t acting like someone threatening a trade war to win concessions; he’s acting like someone who just wants a trade war. Sure enough, he’s reportedly threatening to pull out of the World Trade Organization, the same way he’s suggesting that the U.S. might pull out of NATO.

.. Whatever claims Trump makes about other countries’ misbehavior, whatever demands he makes on a particular day, they’re all in evident bad faith. Mr. Art of the Deal doesn’t want any deals. He just wants to tear things down.

.. The institutions Trump is trying to destroy were all created under U.S. leadership in the aftermath of World War II. Those were years of epic statesmanship — the years of the Berlin airlift and the Marshall Plan, in which America showed its true greatness. For having won the war, we chose not to behave like a conqueror, but instead to build the foundations of lasting peace.

Thus the General Agreement on Tariffs and Trade, signed in 1947 — at a time of overwhelming U.S. economic dominance — didn’t seek a privileged position for American products, but instead created rules of the game to promote prosperity around the world. Similarly, NATO, created in 1949 — at a time of overwhelming U.S. military dominance — didn’t seek to lock in our hegemony. Instead, it created a system of mutual responsibility that encouraged our allies, including our defeated former enemies, to see themselves as equals in preserving our mutual security.

.. anything that weakens the Western alliance helps Vladimir Putin; if Trump isn’t literally a Russian agent, he certainly behaves like one on every possible occasion.

.. Trump obviously dislikes anything that smacks of rule of law applying equally to the weak and the strong. At home, he pardons criminal bigots while ripping children away from their parents. In international relations, he consistently praises brutal strongmen while heaping scorn on democratic leaders.

..

He may complain that other countries are cheating and taking advantage of America, that they’re imposing unfair tariffs or failing to pay their share of defense costs. But as I said, those claims are made in bad faith — they’re excuses, not real grievances. He doesn’t want to fix these institutions. He wants to destroy them.

.. Alternatively, you might have thought that big business, which is deeply invested, literally, in the existing world order would protest effectively. So far, however, it has been utterly ineffectual. And while talk of trade war sometimes causes the stock market to wobble, as far as I can tell, investors still aren’t taking this seriously: They imagine that Trump will bluster and tweet for a while, then accept some cosmetic policy changes and call it a win.

But that kind of benign outcome looks increasingly unlikely, because Trump won’t take yes for an answer. He doesn’t want negotiations with our allies and trading partners to succeed; he wants them to fail. And by the time everyone realizes this, the damage may be irreversible.

In the second year of his presidency, Donald Trump has doubled down on his “America First” brand of economic nationalism, by making impossible demands of US allies and escalating a multi-front trade war of his own making. In doing so, however, he has all but guaranteed that Americans themselves will bear the costs.

President Donald Trump may fancy himself a builder, but when it comes to international treaties and norms, he has proved to be a one-man wrecking crew. And now, the chaos appears to be spreading and deepening.

.. THE TRUTH ABOUT NAFTA

For decades after World War II, Mexico pursued many of the same disastrous economic policies as other developing countries. It maintained high protectionist barriers for manufactured goods, and relied heavily on commodity exports, particularly oil. As a result, it experienced recurrent stop-go cycles, whereby accelerating inflation and ballooning balance-of-payments deficits would force a round of austerity, only for the process to repeat itself after increases in commodity prices, but at a slower rate of growth each time. Not surprisingly, the growth rate during these years waxed and waned dramatically, and by the start of 1989, Mexico’s per capita income was around $2,393 – about 11% that of the US.

.. at the time, the average US tariff on manufactured imports was around 2%, while Mexico’s average tariff on US exports was around 10%. It was clear from the start that the US would gain more from improved access to the Mexican market than vice versa.

.. Ross Perot famously warned that an FTA with Mexico would result in “a giant sucking sound going south.” Of course, nothing of the sort happened.

NAFTA entered into force on January 1, 1994, and between 1993 and 2000, US unemployment fell from 6.9% to 4%. Today, it stands at 3.8% – its lowest point in almost two decades.

.. Some of the demands directed at Mexico, in particular, are so outrageous that no country could ever accept them. Others, such as the US proposal for more stringent rules of origin (which require that a certain percentage of an imported article be fabricated within the NAFTA trade bloc), are very problematic, but a compromise can probably be reached.

.. One of the US’s most disruptive tactics has been to demand that Mexico bring its auto workers’ pay up to the level of their US counterparts. The minimum wage in Mexico is currently around $4 per day, and around $6 per day in manufacturing industries. But the wage floor US negotiators have reportedly demanded is $16 per hour – 21 times the average wage in Mexican manufacturing.

.. it is inconceivable that the Mexican electorate would stand for one segment of workers earning $128 per day while everyone else still earned an average of $4-6 per day.

.. the Trump administration’s demand is so absurd that even the US auto industry opposes it , not least for what it would do to US producers’ value chain.

.. Another impossible US demand, which would affect Canada as much as Mexico, is a sunset clause that would force each government to renew the renegotiated NAFTA every five years. The fact that the entire deal could potentially expire every five years would create a permanent state of uncertainty

.. The Trump administration has justified the tariffs on national-security grounds, which makes absolutely no sense when one considers that US allies are bearing the brunt of the costs.

.. The Trump administration’s approach to both allies and adversaries represents the worst kind of “managed trade,” which the US and other countries with market-based economies have long condemned.

South Korea did not achieve strong, sustained growth until it liberalized its trade and other economic policies, starting around 1960, with the encouragement of the US.

.. South Korea must now create an administrative apparatus to limit its steel producers’ exports to the US. That means tracking 52 different categories of steel to ensure that exports remain at or below 70% of their 2014-2017 levels.

.. there is a need to monitor and regulate the inflow of steel and aluminum, whether by the US, South Korea, or both. For the US, expanding its own customs service to perform this task would carry enormous administrative costs

.. the new dispensation will likely lead to all manner of influence peddling as firms try to win scarce licenses from customs officials

.. There are around 80,000 jobs in the US steel industry, more than 900,000 jobs in the US auto industry, and millions more in other industries that use steel or aluminum.

.. by protecting domestic producers, the Trump administration is raising steel and aluminum prices within the US, while reducing them in the rest of the world. In essence, Trump is conceding even more cost advantages to non-US producers, for no good reason.

.. After World War II, the US led the way in establishing a rules-based trading system, first with the General Agreement on Trade and Tariffs, and then with its successor, the World Trade Organization. The past 73 years have shown that when there are legitimate grievances between trading partners on issues such as high-tech secrets, bilateral efforts to resolve them often prove ineffective, whereas action taken through the WTO has a strong track record. Unless and until the Trump administration recognizes this fact, Americans themselves will bear the costs of its disastrous trade policies.